Question

An inventor claims to have conceived of a second lawchallenging heat engine. (See H. Apsden, "The Electronic Heat Engine," Proceedings 27th International Energy Conversion Engineering Conference, 4.357-4.363, 1992. Also see U.S. Patent No. 5,101,632.) By artfully using mirrors the heat engine would "efficiently convert abundant environmental heat energy at the ambient temperature to electricity." Write a paper explaining the principles of operation of the device. Does this invention actually challenge the second law of thermodynamics? Does it have commercial promise? Discuss,

Short answer

The invention seems to challenge the second law of thermodynamics and lacks empirical support, making its commercial promise doubtful.

Step-by-step solution

Understand the Heat Engine Concept

A heat engine is a device that converts thermal energy into mechanical energy or electricity. Traditional heat engines operate by moving heat from a hotter area to a cooler one, thus doing work in the process.

Review the Invention's Principles of Operation

The described heat engine uses mirrors to supposedly harness ambient heat energy and convert it into electricity. Mirrors might be intended to focus or concentrate heat energy, but the exact mechanism needs more clarification.

Second Law of Thermodynamics

The second law of thermodynamics states that heat cannot spontaneously flow from a colder body to a hotter body without external work being performed. It implies that the conversion of all heat energy into work without losses is impossible.

Analyze the Invention Against the Second Law

Considering the second law, an engine operating solely on ambient heat and converting it completely into electricity without an external temperature gradient or without external work seems to challenge the law. The second law asserts that some energy must always be lost to inefficiency.

Evaluate Commercial Promise

To have commercial promise, an invention must not only be theoretically sound but also practical and efficient. Due to the second law constraints, if the invention claims complete conversion of ambient heat to electricity, it remains highly doubtful without empirical evidence or rigorous testing.

Summarize Findings

The principles of operation appear speculative without clear adherence to the second law of thermodynamics. Thus, it poses significant challenges to its validity and commercial viability.

Key concepts

heat engine

To understand the second law of thermodynamics and how this invention supposedly works, we need to first grasp the concept of a heat engine. A heat engine is a device that transforms thermal energy into mechanical energy or electricity.
For example, steam engines, car engines, and even power plants. These engines operate on a simple principle: heat moves from a hot source to a cooler sink, producing energy in the process.
Here's a breakdown of how a traditional heat engine works:

• Heat Source: A high-temperature source provides heat.
• Working Substance: A medium, like steam or air, absorbs the heat and expands.
• Heat Sink: This is the cooler area where the waste heat is released.

The engine does work (like moving pistons or turning turbines) as the working substance moves through these stages.
This clear pathway from hot to cool areas makes it possible for the engine to do work efficiently.

energy conversion

Next, let’s delve into energy conversion. The aim of a heat engine is to convert energy from one form to another. Specifically, from thermal (heat) to mechanical or electrical energy.
In the context of the heat engine described in the exercise, the idea is to use mirrors to convert ambient heat (thermal energy) into electricity. But how do we typically achieve energy conversion in engines?
Here's a simple explanation:

• Energy Input: Heat energy is supplied to the system.
• Energy Transfer: This heat energy is converted by the working substance. It can be used to do mechanical work, like moving pistons or generating electricity.
• Energy Output: After doing useful work, leftover energy is released, typically as waste heat.

We can’t convert all heat into work because of energy inefficiencies inherent in the process. This brings us to the core principle governing these conversions: the second law of thermodynamics.

thermodynamic efficiency

Let's discuss thermodynamic efficiency, especially in the context of the second law of thermodynamics. This law states that no heat engine can be 100% efficient.
Some energy is always lost to waste heat. This explains why the claimed invention in the exercise seems to challenge established science. According to the second law:

• Heat naturally flows from a hot body to a cooler one.
• Some energy must always be converted to not useful work, mainly waste heat.

In the described invention, mirrors supposedly focus ambient heat and convert it into electricity. However, without an external temperature gradient or external work, this would defy the second law.
Thus, even if the concept appears intriguing, it faces fundamental issues of practical efficiency and adherence to thermodynamic principles.